Choose the word that can substitute the given group of words. A sound that cannot be heard

Inaudible  Audacious  Autonomous  Delible

Inaudible

The word that can substitute the given group of words "a sound that cannot be heard" is inaudible. Inaudible means not able to be heard. Audacious means bold or daring. Autonomous means self-governing. Delible means capable of being erased or removed.